1. Field of the Invention
This invention relates to refrigeration service equipment in transferring refrigerant from one closed system to another closed system, and particularly to a system for filling smaller refrigerant containers from a large container.
2. General Description of the Prior Art
Refrigeration and air-conditioning service personnel employ relatively small tanks of refrigerant in liquid form, typically holding 5 to 150 pounds, being a size that is readily transportable to and between jobs. The amount of refrigerant in such tanks is fairly rapidly used up, requiring that the tanks be filled fairly frequently. They are then refilled from a larger container of liquid refrigerant, and the problem is in effecting transfer, particularly to do so in a safe manner. The common refrigerants used are Freon 12, 22, and 502, these having a progressive boiling point, with Freon 12 boiling at -21.6.degree. F. at 0 PSI, and Freon 502 boiling at -49.5.degree. F. at 0 PSI. These characteristics are typically utilized in the transfer of refrigerant by heating the larger supply container to a temperature higher than the smaller container to create a higher pressure in the larger container than in the smaller one. The problem is that a little too much heat will cause excessive pressure and is likely to cause an explosion, and such has occurred many times and a good many people have been killed. Alternately, transfer may be effected by lowering the temperature of the smaller container below that of the larger container, but this is a quite lengthy process and thus not efficient.